Calcification in free-living coralline algae is strongly influenced by morphology: Implications for susceptibility to ocean acidification

• Published in: Scientific Reports
• Main Authors: Schubert, Nadine, Hofmann, Laurie C., Almeida Saá, Antonella C., Moreira, Anderson Camargo, Arenhart, Rafael Güntzel, Fernandes, Celso Peres, de Beer, Dirk, Horta, Paulo A., Silva, João
• Other Authors: European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement, Fundação para a Ciência e a Tecnologia, National Science Foundation Ocean Sciences International Postdoctoral Research Fellow program, Deutsche Forschungsgemeinschaft, FINEP/Rede CLIMA, Conselho Nacional de Desenvolvimento Científico e Tecnológico
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Multidisciplinary; Ocean acidification
• Online Access: http://dx.doi.org/10.1038/s41598-021-90632-6; http://www.nature.com/articles/s41598-021-90632-6.pdf; http://www.nature.com/articles/s41598-021-90632-6

Abstract Rhodolith beds built by free-living coralline algae are important ecosystems for marine biodiversity and carbonate production. Yet, our mechanistic understanding regarding rhodolith physiology and its drivers is still limited. Using three rhodolith species with different branching morphologies, we investigated the role of morphology in species’ physiology and the implications for their susceptibility to ocean acidification (OA). For this, we determined the effects of thallus topography on diffusive boundary layer (DBL) thickness, the associated microscale oxygen and pH dynamics and their relationship with species’ metabolic and light and dark calcification rates, as well as species’ responses to short-term OA exposure. Our results show that rhodolith branching creates low-flow microenvironments that exhibit increasing DBL thickness with increasing branch length. This, together with species’ metabolic rates, determined the light-dependent pH dynamics at the algal surface, which in turn dictated species’ calcification rates. While these differences did not translate in species-specific responses to short-term OA exposure, the differences in the magnitude of diurnal pH fluctuations (~ 0.1–1.2 pH units) between species suggest potential differences in phenotypic plasticity to OA that may result in different susceptibilities to long-term OA exposure, supporting the general view that species’ ecomechanical characteristics must be considered for predicting OA responses.